Radionuclide angiocardiography has evolved over the past decade from a primitive technique for laboratory investigation to a study routinely performed in a large number of medical centers around the world. This noninvasive procedure provides measurements of ventricular function and hemodynamics which can be used for diagnosis and management of patients with cardiac disorders. The present investigation proposes to develop instrumentation and data processing techniques to enhance the clinical utility of radionuclide angiocardiogram studies. The proportional wire chamber will be used with intravenous injection of tantalum-178 to obtain radionuclide angiocardiogram data. Potential advantages of this instrument over standard gamma cameras are high resolution and sensitivity, low cost and compact size. The use of two proportional wire chambers with bilateral collimators will be explored to obtain four simultaneous views of the heart from different orientations. A second major objective of this investigation will be development of automated data processing techniques which will enhance the accuracy and extend the applicability of radionuclide angiocardiogram studies. Signal processing techniques based upon temporal characteristics of the data will be used to separate counts corresponding to individual cardiac chambers. A computer model will calculate pulsatile volume and flow of each cardiac chamber which best describes observed tracer transit. Since curve separation does not depend upon spatial assumptions, high frequency indicator dilution curves will be similar for each cardiac chamber from four simultaneous views. Borders defined from each of the four orientations will describe the geometric configuration of each chamber, and count intensity will reflect relative chamber volume. Reconstructed three-dimensional count matrices representing real change in radioactivity within each cardiac chamber will be used to measure regional volume changes and to generate simulated three-dimensional dynamic images of each chamber. Phantom, animal and clinical patient studies will verify the accuracy of these techniques which hold great promise for clinical application in patients with cardiac disorders.